Surge protection is a device that protects against transient overvoltages by limiting the frequency and duration of the subsequent current. These devices are also known as lightning arresters, surge protectors or varistors. Surge arresters protect equipment connected to the mains and are also an essential part of the protection of solar installations.
Type 2 (T2 or class C) surge protectors are designed to discharge overvoltages that occur due to switching operations in a circuit (waveform 8/20 μs). Type 2 surge arresters are to be installed behind main power distribution boards (which also contain type 1 surge protection) of the distribution network, in sub-distribution boards (and in apartment buildings in distribution boards of the individual flats).